<template>
    <div
        class="demo-block"
        :class="{ 'hover': hovering }"
        @mouseenter="hovering = true"
        @mouseleave="hovering = false">
        <slot name="source"></slot>
        <div class="meta" ref="meta">
            <div class="description" v-if="$slots.default">
                <slot></slot>
            </div>
            <slot name="highlight"></slot>
        </div>
        <div
            class="demo-block-control"
            ref="control"
            :class="{ 'is-fixed': fixedControl }"
            @click="isExpanded = !isExpanded">
            <transition name="arrow-slide">
                <i :class="[iconClass, { 'hovering': hovering }]"></i>
            </transition>
            <transition name="text-slide">
                <span v-show="hovering">{{ controlText }}</span>
            </transition>
        </div>
    </div>
</template>

<style lang="scss">
    .demo-block {
        border: solid 1px #ebebeb;
        border-radius: 3px;
        transition: .2s;

        &.hover {
            box-shadow: 0 0 8px 0 rgba(232, 237, 250, .6), 0 2px 4px 0 rgba(232, 237, 250, .5);
        }

        code {
            font-family: Menlo, Monaco, Consolas, Courier, monospace;
        }

        .demo-button {
            float: right;
        }

        .source {
            padding: 24px;
        }

        .meta {
            background-color: #fafafa;
            border-top: solid 1px #eaeefb;
            overflow: hidden;
            height: 0;
            transition: height .2s;
        }

        .description {
            padding: 20px;
            box-sizing: border-box;
            border: solid 1px #ebebeb;
            border-radius: 3px;
            font-size: 14px;
            line-height: 22px;
            color: #666;
            word-break: break-word;
            margin: 10px;
            background-color: #fff;

            p {
                margin: 0;
                line-height: 26px;
            }

            code {
                color: #5e6d82;
                background-color: #e6effb;
                margin: 0 4px;
                display: inline-block;
                padding: 1px 5px;
                font-size: 12px;
                border-radius: 3px;
                height: 18px;
                line-height: 18px;
            }
        }

        .highlight {
            pre {
                margin: 0;
            }

            code.hljs {
                margin: 0;
                border: none;
                max-height: none;
                border-radius: 0;

                &::before {
                    content: none;
                }
            }
        }

        .demo-block-control {
            border-top: solid 1px #eaeefb;
            height: 44px;
            box-sizing: border-box;
            background-color: #fff;
            border-bottom-left-radius: 4px;
            border-bottom-right-radius: 4px;
            text-align: center;
            margin-top: -1px;
            color: #d3dce6;
            cursor: pointer;
            position: relative;

            &.is-fixed {
                position: fixed;
                bottom: 0;
                width: 100%;
            }

            i {
                font-size: 16px;
                line-height: 44px;
                transition: .3s;
                &.hovering {
                    transform: translateX(-40px);
                }
            }

            > span {
                position: absolute;
                transform: translateX(-30px);
                font-size: 14px;
                line-height: 44px;
                transition: .3s;
                display: inline-block;
            }

            &:hover {
                color: #409EFF;
                background-color: #f9fafc;
            }

            & .text-slide-enter,
            & .text-slide-leave-active {
                opacity: 0;
                transform: translateX(10px);
            }

            .control-button {
                line-height: 26px;
                position: absolute;
                top: 0;
                right: 0;
                font-size: 14px;
                padding-left: 5px;
                padding-right: 25px;
            }
        }
    }
</style>

<script type="text/babel">

    export default {
        name: 'demo-block',
        data () {
            return {
                hovering: false,
                isExpanded: false,
                fixedControl: false,
                scrollParent: null
            }
        },

        props: {
            jsfiddle: Object,
            default () {
                return {}
            }
        },

        methods: {

            scrollHandler () {
                const { top, bottom, left } = this.$refs.meta.getBoundingClientRect()
                this.fixedControl = bottom > document.documentElement.clientHeight &&
                    top + 44 <= document.documentElement.clientHeight
                this.$refs.control.style.left = this.fixedControl ? `${ left }px` : '0'
            },

            removeScrollHandler () {
                this.scrollParent && this.scrollParent.removeEventListener('scroll', this.scrollHandler)
            }
        },

        computed: {
            lang () {
                return this.$route.path.split('/')[1]
            },

            iconClass () {
                return this.isExpanded ? 'el-icon-caret-top' : 'el-icon-caret-bottom'
            },

            controlText () {
                return this.isExpanded ? '隐藏代码' : '显示代码'
            },

            codeArea () {
                return this.$el.getElementsByClassName('meta')[0]
            },

            codeAreaHeight () {
                if (this.$el.getElementsByClassName('description').length > 0) {
                    return this.$el.getElementsByClassName('description')[0].clientHeight +
                        this.$el.getElementsByClassName('highlight')[0].clientHeight + 20
                }
                return this.$el.getElementsByClassName('highlight')[0].clientHeight
            }
        },

        watch: {
            isExpanded (val) {
                this.codeArea.style.height = val ? `${ this.codeAreaHeight + 1 }px` : '0'
                if (!val) {
                    this.fixedControl = false
                    this.$refs.control.style.left = '0'
                    this.removeScrollHandler()
                    return
                }
                setTimeout(() => {
                    this.scrollParent = document.querySelector('.page-component__scroll > .el-scrollbar__wrap')
                    this.scrollParent && this.scrollParent.addEventListener('scroll', this.scrollHandler)
                    this.scrollHandler()
                }, 200)
            }
        },

        mounted () {
            this.$nextTick(() => {
                let highlight = this.$el.getElementsByClassName('highlight')[0]
                if (this.$el.getElementsByClassName('description').length === 0) {
                    highlight.style.width = '100%'
                    highlight.borderRight = 'none'
                }
            })
        },

        beforeDestroy () {
            this.removeScrollHandler()
        }
    }
</script>
